1. Field
One or more embodiments relate to technology and techniques for detecting light and generating an image according to the detected light.
2. Description of the Related Art
An image sensor detects incident light and generates image data corresponding to the detected light. Generally, the image sensor includes an infrared light (IR) cutoff filter provided at an initial light incidence portion, e.g., an upper part, of the image sensor, a color filter array (CFA) provided below the IR cutoff filter at a middle part of the image sensor, and a photodetector provided below the CFA at a lower part of the image sensor.
The IR cutoff filter is a type of low pass filter (LPF) which cuts off light having a wavelength of about 650 nm and above, that is, infrared light. The color filter array is a band pass filter (BPF) which selectively passes visible light of a predetermined wavelength range such as respective red light (R), green light (G), and blue light (B) among light of a wavelength range of about 400 nm to 700 nm. For example, the color filter array may be implemented using a Bayer filter, where the different filtered lights of different colors are arranged in a Bayer pattern. Respective filters in a Bayer pattern may include 50% G filters, 25% R filters, and 25% B filters, with repeated combinations of RG and GB. The Bayer patterns have been referred to as RGBG, GRGB, or RGGB, which respectively represent different relational placements of each of the respective R, G, and B filters. Accordingly, the photodetector detects light after passing through the IR cutoff filter and the color filter array and generates an image signal corresponding to the detected light, with the image signal representing the captured image data.
After each of the R, G, and B filters, if infrared light still exists in the respective filtered light incident on the respective photodetector, the captured image data would include a color distortion due to the infrared light. Accordingly, it is common to cut off infrared light incident to the photodetector by use of the IR cutoff filter. However, despite such color distortion, it may still be necessary to not use an IR cutoff filter, and thus permit IR to be incident on the photodetector, to obtain a high sensitivity image. The IR cutoff filter may be removed to permit a greater amount of light, that is, light of a broader range of wavelengths to be passed to the respective photodetector, so high sensitivity image can be obtained.
In other words, generally, in the image sensor, the use of the IR cutoff filter reduces the color distortion of the image but makes it difficult to obtain a high sensitivity image. If the IR cutoff filter is not used, a high sensitivity image is obtained but the possibility of causing color distortion of the image is increased.